Nu Leonis

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ν Leonis
Leo constellation map.svg
Red circle.svg
Location of ν Leonis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Leo
Right ascension 09h 58m 13.37557s[1]
Declination +12° 26′ 41.2865″[1]
Apparent magnitude (V) 5.15[2]
Spectral type B6 IV[3]
U−B color index −0.13[2]
B−V color index −0.04[2]
Radial velocity (Rv) +14.4[4] km/s
Proper motion (μ) RA: −25.66[1] mas/yr
Dec.: −15.56[1] mas/yr
Parallax (π) 6.53 ± 0.24[1] mas
Distance 500 ± 20 ly
(153 ± 6 pc)
Absolute magnitude (MV) −0.66[5]
Period (P) 137.2978 d
Eccentricity (e) 0.7
Longitude of the node (Ω) 293.7°
Periastron epoch (T) 2419815.9 JD
Semi-amplitude (K1)
20 km/s
Mass 3.37±0.05[7] M
Radius 2.3[8] R
Luminosity 244[7] L
Temperature 9,552[9] K
Rotational velocity (v sin i) 100[7] km/s
Other designations
ν Leo, 27 Leo, BD+13° 2183, HD 86360, HIP 48883, HR 3937, SAO 98876.[10]
Database references

ν Leonis, Latinised as Nu Leonis, is a binary star system in the zodiac constellation of Leo. It is faintly visible to the naked eye with an apparent visual magnitude of 5.15.[2] The distance to this star, based upon parallax measurements,[1] is around 500 light years. At this distance, the visual extinction from interstellar dust is 0.33 magnitudes.[11]

This is a single-lined spectroscopic binary system with an orbital period of 137.3 days and an eccentricity of 0.7.[6] The primary component is a B-type subgiant star with a stellar classification of B6 IV.[3] It has about 3.37 times the mass of the Sun,[7] 2.3 times the Sun's radius,[8] and radiates 244[7] times the luminosity of the Sun from an outer atmosphere with an effective temperature of 9,552 K.[9] The rotation rate is moderate with a projected rotational velocity of 100 km/s.[7] Little is known about the companion.[6]


  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Mermilliod, J.-C. (1986), Compilation of Eggen's UBV data, transformed to UBV (unpublished), SIMBAD, Bibcode:1986EgUBV........0M. 
  3. ^ a b Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819. 
  4. ^ Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick, eds., The Revision of the General Catalogue of Radial Velocities, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E. 
  5. ^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971Freely accessible, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015. 
  6. ^ a b c Harmanec, P.; et al. (May 1985), "A spectroscopic orbit of the late B star 27 Leo", Bulletin Astronomical Institutes of Czechoslovakia, 36: 160–172, Bibcode:1985BAICz..36..160H. 
  7. ^ a b c d e f Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052Freely accessible, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691. 
  8. ^ a b Pasinetti Fracassini, L. E.; et al. (2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) – Third edition – Comments and statistics", Astronomy & Astrophysics, 367: 521–24, arXiv:astro-ph/0012289Freely accessible, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451. 
  9. ^ a b McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037Freely accessible, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x. 
  10. ^ "* nu. Leo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-09-29. 
  11. ^ van Belle, Gerard T.; von Braun, Kaspar (2009), "Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars", The Astrophysical Journal, 694 (2): 1085–1098, arXiv:0901.1206Freely accessible, Bibcode:2009ApJ...694.1085V, doi:10.1088/0004-637X/694/2/1085.